If you stir it more often to increase o2, you'll give the aerobic bacteria a leg up on the anaerobic cutting down on the smell. A good active compost pile smells "earthy".

Also, you could have a stalled compost pile, or one just not active to handle the large amount of grain you're putting in. Check it in the early morning, give it a good stir with a shovel, and if you see steam or it feels warm to your hand, then you've got a good active compost going. If not, then add a shovel full of dirt, and begin to stir it every 3-5 days, more in the beginning to kick off the microbes you'll want doing the work.

Another good sign of active compost, would be a white/gray mold looking thing growing on the top of the compost before you stir it. It's not actually mold, it's one of those beneficial bacteria, and just what they look like when doing their thing.

I've had the pleasure of smelling decomposing grains. Once behind River Horse Brewing here in NJ and once in my kitchen when i forgot the garbage after 48hrs. It smells ALOT like a dead rat behind a furnace for a week.